This invention relates to a variable displacement pump arranged to supply a lubricant to sliding portions of an internal combustion engine for a vehicle, and a variable valve actuating system arranged to control an actuation characteristic of valves of the engine.
Published Japanese Patent Application Publication No. 5-79469 shows a variable displacement vane pump including a pump housing; an induction opening and a discharge opening located on the both side portions of the pump housing; a driving shaft positioned at a central portion of the pump housing, and to which the torque is transmitted from a crank shaft of an internal combustion engine; a rotor disposed within the pump housing, connected with the driving shaft, and supporting a plurality of vanes located on the outer circumference of the rotor, and arranged to move in the radial direction; and a cam ring swingably disposed on the outer circumference side of the rotor in the eccentric state, and having an outer circumference surface on which ends of the vanes are slidably abutted.
This cam ring is arranged to be swung about a pivot pin in a direction to decrease the eccentric quantity, in accordance with the pump discharge pressure introduced into a hydraulic control chamber separated by a seal member in the outer circumference portion. Moreover, the cam ring is arranged to be swung by a spring force of a single coil spring arranged to push a lever portion integrally formed with the cam ring on the outer circumference, in a direction to increase the eccentric quantity.
That is, in an initial state, the cam ring is urged by the spring force of the coil spring, in the direction in which the eccentric quantity becomes maximum. On the other hand, when the hydraulic pressure within the hydraulic control chamber is equal to or greater than a predetermined quantity, the cam ring is swung against the spring force of the coil spring, in the direction to decrease the eccentric quantity so as to decrease the discharge pressure.